Fix Github Enterprise Login (Deduplicate api-url generate code)

[uanid]

Hello,

I saw #524, Also I tested with latest commits. But Login to Github Enterprise Server with PAT not works. (See #527) Because Github Etnerprise Server's API url pattern is https://${hostname}/api/v3.

Changes

This PR deduplicates api-url generate codes.

Github Enterprise API url reference

https://docs.github.com/en/[email protected]/rest/reference/users

[pbsureja]

Thank you @Uanid for fixing this and @codebytere for reviewing this 🙂 . Do we know whose approval from maintainers do we need here ?

[Araxeus]

@pbsureja want to make the same PR in my fork? 🙂 https://github.com/Araxeus/gitify